Pulse wave measuring apparatus that can obtain optimum pressurization force of pressure sensor

Abstract

A pulse wave measuring apparatus extracts a direct current component from a pressure value obtained from a sensor pressure, and defines the pressurization force of the cuff as the optimum pressurization force when that direct current component is stable. Following determination of the optimum pressurization force, the pulse wave measuring apparatus monitors whether the direct current component obtained from the pressure sensor is optimum or not, and adjusts the pressure, when not. By determining the rising sharpness of the peak and waveform distortion in the sphygmographic waveform, determination is made whether the pressurization force of the cuff is appropriate or not to carry out further adjustment of pressure, as necessary.

What is claimed is: 
     
       1. A pulse wave measuring apparatus comprising:
 a pressure sensor detecting an intra-arterial pressure waveform superficial of a body, 
 an acquiring unit acquiring a direct current component from a pressure value output from said pressure sensor, and 
 a defining unit including means for detecting a site where said direct current component is stable, for defining a pressurization force of pressing said pressure sensor against a body surface as an optimum pressurization force, when said direct current component is stable. 
 
     
     
       2. The pulse wave measuring apparatus according to  claim 1 , wherein said acquiring unit acquires said direct current component from an average value between predetermined intervals of pressure values output from said pressure sensor. 
     
     
       3. The pulse wave measuring apparatus according to  claim 1 , wherein said acquiring unit acquires said direct current component from an intermediate point between a highest value and a smallest value in a predetermined interval of pressure values output from said pressure sensor. 
     
     
       4. The pulse wave measuring apparatus according to  claim 1 , wherein said acquiring unit acquires said direct current component using a low pass filter on pressure values output from said pressure sensor. 
     
     
       5. The pulse wave measuring apparatus according to  claim 1 , further comprising a booster unit altering said pressurization force by applying pressure at one of a constant rate and an arbitrary rate. 
     
     
       6. The pulse wave measuring apparatus according to  claim 5 , further comprising a first adjustment unit comparing said direct current component at a time when said optimum pressurization force is defined with a direct current component after altering said pressurization force, and carrying out adjustment such that the direct current component after altering said pressurization force does not exceed said direct current component at the time when said optimum pressurization force was defined. 
     
     
       7. The pulse wave measuring apparatus according to  claim 1 , further comprising a suction unit altering said pressurization force by reducing pressure at one of a constant rate and an arbitrary rate. 
     
     
       8. The pulse wave measuring apparatus according to  claim 7 , further comprising a first adjustment unit comparing said direct current component at a time when said optimum pressurization force is defined with a direct current component after altering said pressurization force, and carrying out adjustment such that the direct current component after altering said pressurization force does not exceed said direct current component at the time when said optimum pressurization force was defined. 
     
     
       9. The pulse wave measuring apparatus according to  claim 1 , further comprising:
 a determination unit determining whether the pressurization force of said pressure sensor against said body surface is appropriate or not based on a sphygmographic waveform detected by said pressure sensor, and 
 an adjustment unit adjusting said pressurization force after defining said optimum pressurization force based on said determination result. 
 
     
     
       10. A computer-readable medium containing instructions for causing a computer to execute control of a pulse wave measuring apparatus including a pressure sensor detecting an intra-arterial pressure waveform superficial of a body, by a method comprising:
 acquiring a direct current component from a pressure value output from said pressure sensor obtained from said pulse wave measuring apparatus, and 
 detecting a site where said direct current component is stable, for defining a pressurization force of pressing said pressure sensor against a body surface as an optimum pressurization force, when said direct current component is stable.